1. Field of the Invention
The present invention relates to a legged mobile robot which is capable of recognizing the positional relationship between its legs and an obstacle to its walking from image data captured through a vision sensor.
2. Description of the Related Art
Autonomous legged mobile robots have a vision sensor such as a CCD (Charge-Coupled Device) camera, for example. An autonomous legged mobile robot equipped with such a CCD camera recognizes the position of an obstacle present in the course of robot walking from image data obtained by the CCD camera, and walks in a manner to negotiate the recognized obstacle. In order to achieve a wider range of vision, the CCD camera is generally mounted on an upper end, e.g., a head, of the body of the legged mobile robot.
Legged mobile robots are expected to act in a three-dimensional space containing obstacles such as a staircase, etc., in which other types of robots such as wheeled robots cannot easily move. For a legged mobile robot to freely move in a three-dimensional space, it is necessary to accurately calculate the positional relationship between a leg of the robot, particularly, a foot to be landed on the floor and an obstacle present in the course of robot walking. However, since the legged mobile robot has a number of joints between the foot of the leg and the head thereof, it is difficult to accurately calculate the positional relationship between the foot and the obstacle.
In view of the above drawback, there has been proposed a legged mobile robot having a camera mounted on the foot of a leg thereof, as disclosed in Japanese laid-open utility model publication No. 5-93778. When the position of an obstacle to the legged mobile robot is recognized by the camera on the foot of the leg, the legged mobile robot can accurately calculate the positional relationship between the foot and the obstacle because the calculations are free of positioning errors of the joints of the robot.
However, the camera installed on the foot of the leg is disadvantageous in that the camera tends to be easily damaged or smeared by the environment in which the robot walks, and results in an increase in the weight of the leg that is apt to impair the walking performance of the robot.